Circular saw grinding attachment

ABSTRACT

An attachment is provided for sharpening a blade of a bench saw or a radial arm saw when such a blade is removed from the driven arbor of the saw and is temporarily replaced by a grinding wheel. The attachment has a base and a guide which respectively engage and enter the work table top of the saw and the miter groove formed in the table with a shaft normal to the miter groove interconnecting the base and guide. A plate is mounted on the base so that the plate can be rocked to selected positions about the longitudinal axis of the shaft and about a horizontal axis disposed at right angles to said shaft axis. Securing means is provided to fasten the saw blade to the top of the plate so that the blade can be rotated progressively during the sharpening operation. The plate is fitted with stop means which engage the teeth of the saw blade as it is progressively rotated whereby to properly align other teeth with the grinding wheel.

Unite States Patent [1 1 Glas 1 Sept. 18, 1973 CIRCULAR SAW GRINDINGATTACHMENT [76] Inventor: Dirk Glas, 4976 Rumble St.,

Burnaby, B. O, Canada [22] Filed: Aug. 9, 1971 [21] Appl. No.2 93,118

Primary Examiner-Leonidas Vlachos Attorney-Kellard A. Carter [57]ABSTRACT An attachment is provided for sharpening a blade of a bench sawor a radial arm saw when such a blade is removed from the driven arborof the saw and is temporarily replaced by a grinding wheel. Theattachment has a base and a guide which respectively engage and enterthe work table top of the saw and the miter groove formed in the tablewith a shaft normal to the miter groove interconnecting the base andguide. A plate is mounted on the base so that the plate can be rocked toselected positions about the longitudinal axis of the shaft and about ahorizontal axis disposed at right angles to said shaft axis. Securingmeans is provided to fasten the saw blade to the top of the plate sothat the blade can be rotated progressively during the sharpeningoperation. The plate is fitted with stop means which engage the teeth ofthe saw blade as it is progressively rotated whereby to properly alignother teeth with the grinding wheel.

7 Claims, 3 Drawing Figures It is a common practice for the owners ofbench and radial arm saws to have their circular saws, molding heads andother cutting tools sharpened by means of a special sharpening service.Normally this requires that the dulled tool be removed from the machineand transported to the area providing the'sharpening surface. This istime consuming, relatively costly, and inconvenient especially when thesaw is being operated at a remote building site where no s'aw sharpeningservice is readily available.

The present invention solves the problem of sharpening circular sawblades by providing an attachment which can be used on the machineequipped with the blade whichrequires sharpening. The attachmentproperly supports the blade at selected angles relative to the grindingwheel and allows the blade to be rotated one tooth at a time as eachtooth in turn is sharpened. Furthermore, the attachment can be slidablymounted on the work table of a bench saw or fixedly mounted on a worktable of a radial arm saw whereby the blade of either saw can besharpened quickly, easily and accurately.

In drawings which illustrate a preferred embodiment of the invention,

FIG. 1 is a side elevation of a circular saw grinding attachment inaccordance with the present invention,

FIG. 2 is a plan view of the attachment, and

FIG. 3 is a front elevation of the attachment.

Referring to the drawings, the numeral indicates generally a grindingattachment which is intended for use on either a bench saw or a radialarm saw. Each of these widely used saws has a work table 14 in which amiter groove 15 is formed to extend parallel to the side edges of thework table and between the front and rear edges thereof. Normally, thesaw blade is mounted on a driven arbor (not shown) to rotate whileprojecting through a slot (also not shown) in the table 14 in the caseof a table saw, or a suitable distance above the work table in the caseof a radial arm saw.

The attachment 10 comprises a base 20, a guide 21, and a connectingshaft 22. Guide 21 normally is slidably mounted in the table groove 15so that the shaft 22 just clears the top of the table and is disposed atright angles to said groove, the base then slidably engaging the tabletop. The collar-like base 20 is split as shown at 24 in FIG. 1 and thetwo separated parts of the collar are interconnected by a clamping screw25. This arrangement enables the base 20 to be clamped around the shaft22 near one end thereof. The guide 21 has an upper portion 26 throughwhich an opposite end of the shaft 22 projects and this portion may beprovided with a similar split 27 and clamping screw 28. Thus, the base20 and guide 21 are connected by the shaft 22 so that they can be movedtowards and away from one another as required and furthermore, said baseis rotatably mounted about the longitudinal axis of the shaft foradjustment in a number of selected positions.

v A plate 30 is mounted above the shaft 22 to support a saw blade 32during the grinding operation and this plate issecured to the base 20 bymounting means generally indicated at 34. As shown in FIGS. 1 and 2, themeans 34 comprises an upstanding bracket 35 which is integrally formedon the base 20. The plate 30 has a depending bracket 36 positionedalongside the bracket 35. An adjusting screw 37 interconnects the twofaceto-face brackets 35 and 36 so that the plate 30 can be rocked aboutthe axis of said screw which is parallel to the table groove 15. In FIG.l, the bracket 35 will be seen to have an index mark 38 which readsagainst a graduated scale 39 on the bracket 36. This arrangement enablesthe plate 30 to be tilted as required about a horizontal axis extendingat right angles to the longitudinal axis of the shaft 22.

The plate 30 is provided with securing means generally indicated at 42which serves to rotatably attach a saw blade to the plate 30 forengagement by the grinding wheel. FIGS. land 2 show the means 42 ascomprising a shoulder bolt 43 having a head 44 and a reduced andthreaded lower end 45 (FIG. 1), a washer 47, and a spring 48 which isinterposed between said washer and said'head. Plate 30 is provided witha num ber of threaded holes which are designated as 50 and 51 and 52.These holes 50, 51 and 52 are adapted to receive the threaded lower endof the bolt 43, the holes being spaced apart so that saw blades ofvarying diameter, i.e., 6, 9 and 12 inches, can be attached to the topof the plate 30. The washer 47 bears against the face of the saw and thespring 48 exerts a resilient clamping pressure thereon when the bolt 43is suitably tightened. Thus, the blade 32 is firmly secured to the topof the plate 30 although it is possible to rotate the blade about theaxis of the bolt 43 if a suitable turning force is applied to the edgeof the blade.

Attachment 10 is provided with yieldable stop means generally indicatedat 56 which serves to contact the teeth of the saw blade as the blade isrotated on the plate 30 whereby to hold the blade in a selectedposition. The means 56 is shown to comprise a cylindrical rod 57 whichis carried in a sleeve 58 (FIG. 1) formed on the underside of the plate30 near one end thereof. A flexible stop 58 is secured to one end of therod 57 preferably by means of a pin 59, this stop preferably beingformed on a bendable material which allows it to be curved upwardly froman original straight position shown by dotted lines in FIG. 3 only to anormally assumed position shown by solid lines in FIGS. 1, 2 and 3. Rod57 is rather tightly gripped by the sleeve 58 so that some resistance isoffered to longitudinal and rotational movement of the rod.

in order to sharpen the table saw blade 32 using the grinding attachment10, the blade is removed from its driven arbor and is replaced by agrinding wheel 60, see FIGS. 1 and 2. The attachment 10 is placed on thetable 14 with the base 20 slidably resting on the table top and with theguide 21 slidably received in the miter groove 15.

The blade 32 is then fastened to the plate 30 using the securing means42 and with the bolt 43 being appropriately positioned in a selected oneof the holes 50, 51 or 52 as determined by the diameter of the blade.Bolt 43 is tightened to firmly clamp the blade in place while stillallowing it to be rotated. Preferably, the teeth of the saw blade 32 arepositioned so that they just overhang the adjacent edge of the plate 30.The rod 57 is now extended as required to allow the upwardly curvingstop 58 to enter between two adjacent saw teeth when the blade 30 isrotated. It will be found that the yieldable stop 58 acts as a pawl withthe teeth of the saw blade forming a ratchet whereby the saw blade canbe turned progressively and normally one tooth at a time.

In the drawings, the blade 32 is shown supported by the apparatus in ahorizontal position. This was done for the sake of convenience but,during the sharpening operation now being described, the blade actuallyis tilted downwardly (FIG. 1) towards the grinding wheel 60 so that theteeth being sharpened engage the edge of the wheel near the top surfaceof the table 14. This forward tilting of the blade can be achieved bytemporarily loosening either of the bolts 25 or 28 so that the plate 30can be rocked about the longitudinal axis of the shaft 22 to therequired angle.

Most saw blades are sharpened with the vertical axis of the bracket 36perpendicular to the work table 14 as shown best in FIG. 3. However,some teeth are ground not at right angles to the plane of the blade butat a slight angle thereto so as to provide a suitable clearance. Toaccomplish this type of grinding, the bolt 37 is loosened and the plate30 is rocked to left or right (FIG. 3) to the required angle indicatedby the index mark 38 reading on the scale 39 whereupon said bolt isretightened to maintain the angular setting.

With the grinding wheel 60 rotating, the attachment 10 is moved forwardon the table 14 to present a tooth of the blade to the wheel and toremove the required amount of metal which will sharpen that tooth. Theattachment is then moved back and the blade is turned about thelongitudinal axis of the bolt 43 a distance equal to one tooth. Thismovement causes the stop 58 to click into the next tooth so as toindicate when the tooth to be sharpened is properly aligned with thegrinding wheel 60 and to resist further turning movement of the sawblade on the plate 30. The grinding operation is then repeated tosharpen the saw blade one tooth at a time.

The above described grinding operation is the one used to sharpen atable saw blade but, in the case of a radial arm saw, the procedure isslightly different. The grinding wheel 60, which is then mounted on themovable arbor (not shown) of the radial arm saw, is moved up to the sawblade to sharpen each tooth in turn. The attachment 10 remainsstationary and only the grinding wheel 60 is moved back and forth tosharpen the teeth as the saw blade is rotated on the table 30.

From the foregoing, it will be seen that the present attachment can beused to sharpen either a table saw blade or the blade of a radial armsaw with the sharpening being done in each case quickly and easily aswell as accurately.

1. A grinding attachment for sharpening a saw blade of a saw having awork table in which a miter groove is formed and a driven arbor for saidsaw blade, com prising a base mountable on the work table, a guideenterable into the miter groove, a shaft normal to the miter groove andconnecting the base and guide in spaced relation, a plate above thebase, mounting means securing the plate to the base, and securing meansadapted to rotatably attach a saw blade to the plate for engagement by agrinding wheel mounted on the driven arbor.

2. A grinding attachment as claimed in claim I, and including yieldablestop means carried by the plate progressively to engage each cuttingtooth of the saw blade and thereby align another cutting tooth with thegrinding wheel.

3. A grinding attachment as claimed in claim 1, in which said base issupported to be rocked about the longitudinal axis of the shaft wherebythe plate can be adjusted to a selected inclined position relative tothe work table.

4. A grinding attachment as claimed 'in claim 1, in which said securingmeans comprises a shoulder bolt enterable into a selected one of aplurality of spaced apart and threaded holes formed in the plate, awasher and a spring mounted on the shoulder bolt and cooperatingtherewith to exert resilient pressure clamping the saw blade to theplate.

5. A grinding attachment as claimed in claim 2, in which said stop meansis adjustably carried'by the plate to accommodate saw blades of varyingdiameters.

6. A grinding attachment as claimed in claim 1, in which said mountingmeans includes a graduated scale and a co-operating index mark.

7. A grinding attachment for sharpening a saw blde of a saw having awork table in which a miter groove is formed and a driven arbor fortemporarily supporting a grinding wheel, comprising a base mountable onthe work table, a guide enterable into the miter groove, a shaft normalto the miter groove and connecting the base and guide in spacedrelation, said base being adjustable about the longitudinal axis of theshaft, a plate above the base, mounting means securing the plate to thebase for rocking movement about an axis perpendicular to thelongitudinal axis of the shaft, securing means adapted to rotatablyattach a saw blade to the plate for engagement by the grinding wheel,said securing means comprising a shoulder bolt enterable into a selectedone of a plurality of spaced apart and threaded holes formed in theplate, a washer and a spring mounted on the shoulder bolt andco-operating therewith to exert resilient pressure clamping the sawblade to the plate, and yieldable stop means carried by the plateprogressively to engage each cutting tooth of the saw blade and therebyalign another cutting tooth with the grinding wheel.

ll t 9 =9

1. A grinding attachment for sharpening a saw blade of a saw having awork table in which a miter groove is formed and a driven arbor for saidsaw blade, comprising a base mountable on the work table, a guideenterable into the miter groove, a shaft normal to the miter groove andconnecting the base and guide in spaced relation, a plate above thebase, mounting means securing the plate to the base, and securing meansadapted to rotatably attach a saw blade to the plate for engagement by agrinding wheel mounted on the driven arbor.
 2. A grinding attachment asclaimed in claim 1, and including yieldable stop means carried by theplate progressively to engage each cutting tooth of the saw blade andthereby align another cutting tooth with the grinding wheel.
 3. Agrinding attachment as claimed in claim 1, in which said base issupported to be rocked about the longitudinal axis of the shaft wherebythe plate can be adjusted to a selected inclined position relative tothe work table.
 4. A grinding attachment as claimed in claim 1, in whichsaid securing means comprises a shoulder bolt enterable into a selectedone of a plurality of spaced apart and threaded holes formed in theplate, a washer and a spring mounted on the shoulder bolt andco-operating therewith to Exert resilient pressure clamping the sawblade to the plate.
 5. A grinding attachment as claimed in claim 2, inwhich said stop means is adjustably carried by the plate to accommodatesaw blades of varying diameters.
 6. A grinding attachment as claimed inclaim 1, in which said mounting means includes a graduated scale and aco-operating index mark.
 7. A grinding attachment for sharpening a sawblde of a saw having a work table in which a miter groove is formed anda driven arbor for temporarily supporting a grinding wheel, comprising abase mountable on the work table, a guide enterable into the mitergroove, a shaft normal to the miter groove and connecting the base andguide in spaced relation, said base being adjustable about thelongitudinal axis of the shaft, a plate above the base, mounting meanssecuring the plate to the base for rocking movement about an axisperpendicular to the longitudinal axis of the shaft, securing meansadapted to rotatably attach a saw blade to the plate for engagement bythe grinding wheel, said securing means comprising a shoulder boltenterable into a selected one of a plurality of spaced apart andthreaded holes formed in the plate, a washer and a spring mounted on theshoulder bolt and co-operating therewith to exert resilient pressureclamping the saw blade to the plate, and yieldable stop means carried bythe plate progressively to engage each cutting tooth of the saw bladeand thereby align another cutting tooth with the grinding wheel.